In an internal combustion engine such as a diesel engine equipped in a vehicle, a piston is reciprocated by burning fuel to obtain a rotational force. The piston is repeatedly exposed to high-temperature combustion gas, and thus a large thermal load is repeatedly applied to the piston. Therefore, it is necessary to pay attention to excessive temperature rise of the piston which exerts a huge influence on the durability of the piston, so a fuel injection timing is changed so that the piston temperature does not rise too much.
For example, a control system of an internal combustion engine has been proposed in which an in-cylinder direct injection spark ignition internal combustion engine sets the fuel injection timing by an injector near an intake bottom dead center when a piston temperature is equal to or lower than a temperature threshold value and sets the fuel injection timing by the injector near an intake top dead center when the piston temperature is higher than the temperature threshold value (see Patent Literature 1, for example).